Fixed #24813 -- Documented {% include %} debug behavior variance

    {% include "name_snippet.html" with greeting="Hi" only %}

If the included template causes an exception while it's rendered (including

if it's missing or has syntax errors), the behavior varies depending on the

:class:`template engine's <django.template.Engine>` ``debug`` option (if not

set, this option defaults to the value of :setting:`DEBUG`). When debug mode is

turned on, an exception like :exc:`~django.template.TemplateDoesNotExist` or

:exc:`~django.template.TemplateSyntaxError` will be raised; otherwise

``{% include %}`` silences any exception that happens while rendering the

included template and returns an empty string.

.. note::

    The :ttag:`include` tag should be considered as an implementation of

    "render this subtemplate and include the HTML", not as "parse this